This invention relates to a one-step process for the production of polyamines containing primary amino groups, preferably aromatically bound amino groups and to a process for producing a polyurethane(urea) therefrom.
It is known that isocyanates can be converted into amines by acidic or basic hydrolysis, as shown for example in N.V. Sidgwick, The Organic Chemistry of Nitrogen, Clarendon Press, Oxford, page 236 (1966) and in J. March, Advanced Organic Chemistry: Reactions, Mechanism and Structure, McGraw-Hill Book Co., N.Y. page 658 (1968). Sidgwick refers generally to the alkaline hydrolyzability of NCO groups without, however being specific.
Multi-step processes and one-step processes for converting isocyanates to amines have been proposed. For example, DE-A-2,948,419, DE-AS 3,039,600 and DE-OS No. 3,131,252 each disclose a multi-step process. DE-OS No. 3,223,400/EP-97 299, DE-OS No. 3,223,398/EP-97 298 and DE-OS 3,223,397/EP-97 290 each disclose a one-step process. The one-step hydrolysis processes use "ether solvents" together with tertiary amines as catalysts (DE-OS No. 3,223,400), polar solvents (such as dimethylformamide) together with tertiary amines or relatively large quantities of alkali hydroxides, alkali silicates or alkali cyanides as catalysts (DE-OS No. 3,223,398) or polar solvents with carbonates or carboxylates as catalysts (DE-OS No. 3,223,397).
All of the known processes for the production of polyamines are complicated to a greater or lesser extent. Even in the one-step processes, further simplifications which would enable the polyamines to be obtained in an economically even more favorable manner, in even better NCO/NH.sub.2 conversion rates (i.e. higher NH.sub.2 numbers) and in an even smoother reaction would be desirable. More specifically, a process in which
(a) no filtration is necessary, PA1 (b) there is no need for a tertiary amine catalyst to be separated off by distillation, PA1 (c) the quantity of catalyst required may be drastically reduced so that the catalyst may remain in the polyamine, PA1 (d) the conversion of NCO groups into NH.sub.2 groups is substantially quantitative (high NCO/NH.sub.2 conversion rate, i.e. a high amine number approaching the theoretical value), PA1 (e) the proportion of monomeric amines is as small as possible, PA1 (f) there is no accumulation of secondary products requiring disposal and PA1 (g) the polyamines and auxiliaries may be worked up without difficulty
would represent a significant advance over known processes.
It has now surprisingly been found that these and other improvements may be obtained when the one-step hydrolysis of polyisocyanates to polyamines is carried out at certain water/NCO ratios, using certain water-soluble organic solvents and minimal quantities of catalyst under homogeneous reaction conditions. Under these conditions, it is even possible to carry out the hydrolysis at low temperatures.